Urticaria: When a Patient Gets Hives

As your allergist attempts to define the cause of your hives, he/she may first wish to determine whether the problem is an acute problem or whether it is a chronic problem. Hives lasting less than six weeks are usually called “acute urticaria”. With this type of hives, the cause is more likely to be found and the most common causes for acute hives are food allergy, drugs or infections. Obviously, the most common type of infections are viral and it is not unusual for one to have a viral upper respiratory tract (a “cold”, for example) and then one or two weeks after one has recovered then one develops the onset of hives. We believe that the body is able to produce antibodies to the virus during the recovery phase and then those antibodies combine with leftover viral proteins in the blood stream. It is these complexes of viral proteins and antibodies, which then trigger the release of histamine and the onset of hives. Likewise, an individual may develop an immune response to a drug and this may then trigger the events necessary to result in hives. Lastly, foods may also act as an allergen and trigger hives. The medical history, which you provide your physician, is the best clue to the cause of acute hives. For example, if a food is the culprit then there will be a temporal relationship between the onset of hives and the ingestion of the suspect food. Addionally, the onset of hives with any particular hives must be reproducible and will not be responsible to hives only sometimes and then not at other times. Finally, a good physical examination by your physician may help sort out the cause of your hives. There may be physical signs to suggest a specific infectious cause such as viral hepatitis. Or your physician may note that your hives have characteristics, which might suggest that there is inflammation of the blood vessels supplying the skin. Laboratory tests may prove to be a useful adjunct but laboratory tests should never be done without good medical history and physical examination. A quick trip to the emergency department to receive a “steroid shot” for your hives may be a “quick fix” but it may offer very little to sort out the complexities of this disorder and too many corticosteroid injections may have long-term side effects which may be deleterious to your health.
Foods are an obvious candidate to consider as a cause for acute hives. The most common foods that cause hives are nuts, milk, fish, shellfish, eggs, soy and peanuts. Despite a popular conception that strawberries and chocolate are a frequent cause of hives, there is little real scientific evidence to support this common belief. Food allergy in general is much more common in children and this certainly holds true for foods being a cause of hives. It is important to realize that hives may be part of a generalized reaction which has the potential to be life threatening. This generalized reaction is referred to as anaphylaxis and it may occur within minutes of ingesting food to which an individual has developed allergic antibodies. The symptoms of anaphylaxis may include hives all over, difficulty breathing with symptoms that mimic asthma. There may be associated nausea, vomiting and diarrhea. This may eventually result in a drop in blood pressure and a feeling as if one is going to pass out. Hives in this setting represent an emergency and immediate treatment with adrenalin (epinephrine) and antihistamines is imperative. The most common foods associated with anaphylaxis include peanuts, fish, shellfish and nuts and it would be most unusual for one to “out grow” this type of food allergy.

Drugs are another common cause of acute hives. Almost any prescription or over-the-counter (OTC) medication can cause hives. One should not forget to include OTC vitamins, herbs, mineral supplements and cold and sinus medications as potential causes for acute hives. Some of the drugs associated with hives include antibiotics, pain medications, sedatives, tranquilizers and diuretics (fluid pills). Diet supplements, antacids, OTC arthritis medications, laxatives and even eye medications should be considered. In other words, if you have hives it is important to write down all medication and OTC products that you have been taking, and this should be reviewed with your allergist.

Chronic urticaria, by definition, are hives which have been present for longer than six weeks and it is this type of hives which may present the greatest challenge to both the patient and the physician. Indeed, we are able to define a specific cause in only about 15% of patients who present with chronic hives and this type of urticaria is referred to idiopathic urticaria. It is in the understanding of this type of hives that allergists have made the greatest progress in elucidating the mechanisms of hive development. Our current understanding of chronic hives indicates that perhaps 40-50% of patients may have an antibody directed against certain cells, which contain histamine (these cells are called mast cells and basophils). When an antibody activates these cells then they release histamine. The released histamine then contributes to the development of hives. Naturally, a complex sequence of events is cast into play in which inflammatory cells come into the skin. It is this inflammatory aspect of chronic hives, which make the treatment very difficult, even when using very high doses of antihistamines. It is this type of hives in which the patients may benefit the most by consultation with an allergist who understands the complexities of the immune system. As was mentioned previously, hives may simply be a symptom of some underlying medical problem. There is evidence that patients who develop chronic hives may be more prone to the development of autoimmune thyroid disease although there is some debate whether this represents a “cause and effect”. Chronic hives may be associated with certain connective tissue diseases such as systemic lupus erythematosus. These complex associations with a multitude of diverse diseases dictate that chronic idiopathic urticaria deserves a referral to an allergist/immunologist.